Lower eyelid. Lower, inferior, skin that covers the front of the eyeball when closed.

Macula. The focusing portion of the eye that allows us to see fine details clearly.

Optic nerve. A bundle of nerve fibers that connect the retina with the brain. The optic nerve carries signals of light, dark, and colors to the area of the brain (the visual cortex), which assembles the signals into images (for example, our vision).

Posterior chamber. The back part of the eye's interior.

Pupil. The opening in the middle of the iris through which light passes to the back of the eye.

Retina. The light-sensitive nerve layer that lines the back of the eye. The retina senses light and creates impulses that are sent through the optic nerve to the brain.

Sclera. The white visible portion of the eyeball. The muscles that move the eyeball are attached to the sclera.

Suspensory ligament of lens. A series of fibers that connects the ciliary body of the eye with the lens, holding it in place.

Upper eyelid. Top, movable, superior fold of skin that covers the front of the eyeball when closed, including the cornea.

Vitreous body. A clear, jelly-like substance that fills the back part of the eye.